Plural source fluid dispenser with interconnected discharge volume varying means



May 27, 1969 C. HOBBS ll, ETAL PLURAL SOURCE FLU ID DISPENSER WITH INTERCONNECTED Filed Jan. 25, 1967 DISCHARGE VOLUME VARYING MEANS Sheet of 4 INVENTORSI JAMES C.HOBBS,11 ALAN RICHARDSON JONES EUGENE L. SCHULTZ y 7, 1969 J. c. HOBBS ll, ET AL 3,446,400

O D Z E t e e h S C Du E T N I H T I w R Wu PLURAL SOURCE FLUID DISPENS DISCHARGE VOLUME VARYING MEANS Flled Jan. 25. 1967 S E m Eu U R INL m S O U N SH W B D C OR IH A H L C Cm. E S N E N Y MAGS A JAE ATT' YS 3,446,400 CTED J. C. HOBBS II, ET AL LUID DISPENSER WI May 27, 1969 PLURAL SOURCE F TH INTERCONNE DISCHARGE VOLUME VARYING MEANS Sheet Filed Jan. 25. 1967 FIG.4

INVENTORS S 0 E aw w WW .02 T JN n S 0 WV. w B S H d BD i S M O E 5 N E EM MAW L MAE y 7, 1969 J c. HOBBS N, EW 3,446,400

PLURAL SOURCE FLU ID DISPENSER WITH INTERCONNECTED DISCHARGE VOLUME VARYING MEANS Filed Jan. 25. 1967 Sheet 4 of 4 FIG. 5 FIG. 6

43 f 27 I! O O A 2s I f 52 7 57 FIGS L as H 65 i I 64" I g 2s 5 2s 4s 1 0' 67-" I g To h it;

E INVENTORS:

JAMES C.'HOBBS,H ALAN RICHARDSON JONES EUGENE L. SCHULTZ United States Patent 3 446 400 PLURAL SOURCE FLun) DISPENSER WITH IN- TERCONNECTED DISCHARGE VOLUME VARY- ING MEANS ABSTRACT OF THE DISCLOSURE An apparatus for diluting a liquid sample with a suitable diluent. A motor-dn'ven eccentric and yoke assembly are arranged to shift downwardly and upwardly the piston of a fixed-volume diluent chamber for drawing and discharging a measured amount of diluent. As the yoke assembly approaches its lower position, it engages and drives downwardly the piston assembly of a sample chamber communicating with an uncalibrated pipette, and as the yoke assembly is then moved upwardly, the sample and diluent are discharged through the pipette. A valve, driven by the same motor which operates the pistons, controls the fiow of diluent and sample in positive synchronization with piston operation.

Background of the invention It is a common practice in clinical laboratories to prepare dilutions of small specimens of body fluids so that analytical procedures may be carried out on the diluted samples. Ordinarily, the diluting operation is performed manually, using a standard calibrated pipette. Such a procedure is not only time consuming and tedious, but also presents an opportunity for error, especially where a high degree of skill has not been attained by the tech nician and where a high speed of operation is necessary or desirable.

Efforts have been made to develop devices for performing diluting operations mechanically but such devices tend to be cumbersome, complicated, and subject to frequent breakdown. Frequent adjustment of such devices is required in order to maintain a reasonable level .of accuracy. In general, prior efforts have been unsuccessful in developing a diluter which may be operated to mix a sample with a precise amount of diluent by a relatively inexperienced laboratory technician.

Summary of the invention .The diluter of the present invention constitutes a simple and reliable device for automatically diluting samples with selected diluents in predetermined sample-diluent ratios. Specifically, the diluter is capable of discharging a precise fixedamount of any selected diluent along with a predetermined amount of a selected sample, thereby discharging the sample and diluent in a precisely con trolled and predetermined ratio.

The diluter is of simple and reliable construction, having a motor-driven intake and delivery means which draws and discharges precisely-controlled amounts of diluent and sample despite the normal run-on or coasting of such a motor following de-energization thereof. In addition, the device is substantially jam-proof and errorproof in operation and, since it is self-rinsing, it is capable of successively diluting different samples without danger of cross-contamination.

Brief description of the drawing FIGURE 1 is a perspective view illustrating a diluter 3,446,400 Patented May 27, 1969 of the present invention when viewed from the front thereof;

FIGURE 2 is a broken perspective view of the same diluter viewed from the rear thereof;

FIGURE 3 is a broken side elevational view illustrating the operative mechanism of the diluter;

FIGURE 4 is a front elevational view of the diluter with the outer cover thereof removed to illustrate the diluters operating mechanism;

FIGURE 5 is a front elevtaional view similar to FIG- URE 4 but in reduced scale and showing the diluter in a subsequent stage of its operation;

FIGURE 6 is a front elevational view similar to FIG- URE 5 but showing the diluter in a later operational stage;

FIGURE 7 is a front elevational view similar to FIG- URES 5 and 6 but illustrating the diluter in a later stage of operation;

FIGURE 8 is a front elevational view similar to FIG- URES 5-7 but illustrating the diluter in a still later stage of operation.

Description of illustrated embodiment In the embodiment of the invention illustrated in the drawings, the numeral 10 generally designates a diluter having a casing 11 composed of two interfitting casing sections 11a and 1111. As shown most clearly in FIG- URES 2 and 3, casing section 11a is generally C-shaped and defines the top, rear, and bottom walls 12-14 of the casing. Section 1112 is also of C-shaped configuration (when viewed in horizontal section) and defines integral front and side walls 15 and 16, respectively. A rigid tube 17 extends upwardly from top wall 12 and then turns forwardly and downwardly, the tubes downwardly projecting end being coupled by connector sleeve 18 to a downwardly extending pipette 19. Preferably the pipette 19 is formed of glass or other transparent material which can be easily rinsed and wiped free of traces of samples diluted or to be diluted by the device. As will be brought out more clearly hereafter, pipette 19 serves only as a delivery and intake conduit and need not be calibrated.

Casing section 11a also constitutes part of the main frame upon which the operating mechanism of the diluter is mounted. Another frame element takes the form of a vertical partition or mounting plate 20 (FIGURE 3) which has rearwardly turned portions 20a and 20b at its upper and lower ends secured to the upper and lower walls 12 and 14 of casing section 11a. The mounting plate also has rearwardly turned side portions 20c with threaded apertures for receiving screws 21 for interconnecting casing sections 11a and 11b.

An electric motor 22 is secured to the backside of mounting plate 20 and, in combination with gear reduction assembly 23, drives horizontal shaft 24 at a relatively slow rate. FIGURE 3 reveals that shaft 24 extends forwardly through mounting plate 20 and has affixed to its forward end a rotatable drive member or disk 25. The front face of the disk carries an irregularly-shaped cam member 26 which in turn supports an eccentric roller 27. The periphery of the drive disk 25 is provided with circumferentially-spaced recesses 28 to receive the rollerequipped free end portion of arm 29 of microswitch 30. As evident from FIGURE 4, when the arm 29 is in an outwardly extending unflexed state, contacts 31 are spaced apart and the microswitch is open. On the other hand, when disk 25 has rotated into a position wherein the roller-equipped free end portion of the switch arm is no longer received within a recess 28, then switch 30 is closed.

Referring to FIGURES 3 and 4, it will be seen that a valve block 32 is secured by screws 33 to the front of mounting plate 20 above drive disk 25. The upper portion of the block has a horizontally and transversely extending bore 34 which slidably receives an elongated spool valve member 35. The ends of the valve member project outwardly from the through bore of the valve block and are engaged by lever means for the shifting of the valve member between a first position illustrated in FIG- URES 4-6 and a second position illustrated in FIG- URES 7 and 8.

The valve block is also bored from the underside to receive open ended sleeves 36 and 37 which extend downwardly from the valve block in side-by-side parallel relation and which define diluent and sample chambers 38 and 39 respectively. Both of the chambers communicate at their upper ends with bore 34. As indicated in the drawings, diluent chamber 38 is substantially larger in diameter than the sample chamber and slidably receives a piston or plunger 40 extending upwardly through the open lower end thereof. Sample chamber 39 similarly receives a plunger or piston 41. The plunger of the sample chamber may slidably engage the inner wall surface of that chamber or, if desired, may be of substantially smaller diameter than the sample chamber with the lower end of the sample chamber being partially closed to provide an opening of a size sufiicient only for slidably receiving the plunger. Both of the plungers 40 and 41 are provided with downwardly extending rods or shafts 42 and 43, the lower end of the diluent plunger shaft being slidably received and guided by an apertured guide element 44 secured to mounting plate 20 below drive disk 25.

Rotary movement of the drive member 25 is translated into reciprocatory movement of the plungers 40 and 41 by means of eccentric 27 and a cooperating yoke assembly 45. The yoke assembly, illustrated most clearly in FIG- URES 3 and 4, comprises a pair of vertically-spaced and horizontally-extending upper and lower yoke members or plates 46 and 47 rigidly secured to diluent plunger shaft 42. In the illustration given, the plates are apertured to receive the shaft and are thereafter fixed securely to that shaft by set screws 48. It is to be understood, however, that any other means for permanently fixing the plates to the shaft may be used. To insure a rigid interconnection between the parts and to precisely space plates 46 and 47, a spacer element 49 may span the space between the plates and be permanently secured to such plates by any suitable means.

It will be noted that eccentric roller 27 projects forwardly into the space between yoke plates 46 and 47 and is engageable with one or the other of the plates as drive member 25 rotates. Of particular importance is the fact that the diameter of eccentric roller 27 is substantially less than the distance between the spaced yoke plates. In the embodiment illustrated, the distance between the plates is nearly twice the diameter of the roller; however, it is important only that the spacing be greater than the rollers diameter plus the distance measured vertically that the roller will continue to move from its extreme uppermost and lowermost positions because of the momentum or inertia of the driving mechanism after electric power to motor 22 has been interrupted.

The plates of the yoke assembly are apertured at 50 for slidably receiving the shaft 43 of sample displacement plunger 41. The extent of the sliding movement between the parts is limited by an upper stop pin or element 51 secured to the upper end portion of shaft 43 and by a lower stop disk or element 52 secured to the shafts lower end. It is believed apparent that where only a single volume of sample is to be deliverable by the diluter, stop 52 should be permanently located in a position where it will be engaged by the undersurface of yoke plate 47 as the yoke assembly approaches the lower limits of its range of movement. In the illustration given, the diluter is adapted to deliver either of two preselected volume samples depending upon whether a relatively large spacer element 53 or a relatively small spacer element 54 is interposed between stop 52 and yoke plate 47. The spacer elements 53 and 54 are carried by a sleeve member 55 which is vertically bored to receive vertical hexagonal shaft 56. The sleeve is readily slidable along the hexagonal shaft and normally rests upon the lower stop disk 52, contact with the stop disk being made by one of the spacer elements which are part of the sleeve-spacer assembly.

The hexagonal shaft 56 projects upwardly through top wall 12 of the diluter casing and is provided at its upper end with a control knob 57 for rotating the shaft and sleeve-spacer assembly into either a first position wherein the smaller spacer 54 is disposed between stop 52 and yoke plate 47, or into a second position wherein the larger spacer 53 is disposed between the stop and lower yoke plate.

Besides being rotatable into either the first and second positions of adjustment, shaft 56 and knob 57 are movable vertically between the normally raised position illustrated in FIGURE 4 and a lowered position wherein a disk 58 secured to the shaft engages the arm of override switch 59 to close the contacts 60 of that switch. Disk 58 also serves to limit the extent of upward movement of the shaft and knob, by engagement with the undersurface of top wall 12, in response to the upward force exerted by compression spring 61. The compression spring is interposed between a shoulder 62 near the lower end of the shaft and the upper surface of abracket arm 63 secured to mounting plate 20.

Referring again to the diluters valve assembly, spool valve member 35 is shifted between its first and second positions by levers 64 and 65 disposed on opposite sides of valve block 32. The levers have their upper ends in engagement with opposite ends of the spool valve member and are pivotally supported intermediate their ends by mounting screws 66 attached to vertical mounting plate 20. At their lower ends, the levers are provided with rollers 67 engageable by the outer limits of cam 26 as drive member 25 rotates.

Referring to FIGURE 4, it will be seen that the levers 64 and 65 are roughly parallel and are coordinated in their operation to shift valve member 35 in either one direction or the other. Specifically, when the roller 67 of one lever is engaged by cam 26 and urged thereby into its outermost position, the roller of the other lever is pivoted by valve member 35 into an inwardly disposed position in the path of the cam member when the cam has rotated approximately 180 degrees. Thus, as viewed in FIGURE 4, the valve member is urged to the right into its first position upon contact between the cam member and roller 67, and the valve will remain in that position until the cam has rotated approximately 180 degrees and engages the roller of the right-hand lever to shift the valve member to the left into its second position of adjustment.

The spool valve 35 has a pair of reduced spool portions 35a and 35b separated by an intermediate enlargement 350. When the valve is in the first position illustrated in FIGURES 46, pipette 19 and tube 17 directly communicate with sample chamber 39 through connecting tube 68 and port 69. At the same time, diluent chamber 38 is in communication with a suitable diluent source 70 (illustrated diagrammatically in FIGURE 2) by meansof tube 71 and valve port 72 (FIGURE 4).

When the spool valve is in its second position, both the diluent chamber and the sample chamber communicate with the space of bore 34 defined by constriction 35b of the valve member, and port 72 is blocked from communicating with the sample and diluent chambers by valve enlargement 35c.

Operation FIGURE 4 illustrates the diluter in a condition ready for operation, it being assumed that tube 71 is in communication with a source of water or other suitable diluent and that all of the passages of tubes 71, 68, 17, 18, and 19, and the chambers of cylinders 38 and 39 are filled with diluent as a result of prior operation of the device.

The electrical circuit for motor 22 is open because, as shown in FIGURE 4, the rider of switch arm 29 is received within the peripheral recess 28 of the drive member 25, thereby allowing separation of contacts 31. Prior to commencement of operation of the device, the operator rotates control knob 57 into either of its two positions to select the particular volume of sample to be diluted by a fixed volume of diluent. Thereafter, a suitable beaker B (FIGURE 1) containing the liquid sample to be diluted is raised until the tip of the pipette is immersed in the sample. Knob 57 is then depressed to close the contacts of override switch 59. Motor 22 commences operation rotating drive member 25 in a clockwise direction, as viewed in FIGURE 4, to bring eccentric 27 into contact with the upper surface of yoke plate 47. Continued rotation of the drive member and eccentric causes downward movement of the yoke assembly which in turn causes retraction or lowering of diluent plunger 40. Diluent is thereby drawn into the diluent chamber through tube 71 and port 72.

During the initial downward travel of the yoke assembly, sample plunger 43 remains stationary because the shaft of that plunger is freely slidable through the aligned openings of the yoke plates. However, at an intermediate point in the yoke assemblys downward path of travel, the undersurface of lower yoke plate 47 engages one of the spacer elements 53, 54 which in turn rests upon the upper surface of stop 52. Continued downward movement of the yoke assembly thereby causes stop 52, shaft 43, and sample displacement piston 41, into a lowered position. Since the sample chamber is in communication with beaker B through the valveblock and through tubes 68, 17, 18, and 19, a small preselected amount of sample is drawn into the pipette as the sample displacement plunger completes its descent. At no time does the sample dis placement piston descend far enough to draw sample into the valve assembly. Preferably, the parts are proportioned so that the increase in volume of the sample chamber 39 as the plunger descends does not exceed the volume of pipette 19.

FIGURE 5 illustrates the unit just as the undersurface of yoke plate 47 engages spacer 54 and the shaft 43 of the sample displacement plunger commences its downward movement. FIGURE 6 illustrates the relationship of the parts as eccentric 27 has swung just slightly past its lowermost point and, as a result, both the diluent plunger and the sample displacement plunger have been shifted into their lowermost positions. Switch 30 is automatically opened to de-energize the motor because the rider of switch arm 29 has been received in a second peripheral recess 28 of drive member 25. While the motor tends to run on slightly after de-energization, such run-on in no way effects the positions of the sample and diluent plungers because, as previously described, the space between upper and lower yoke plates 46 and 47 is substantially greater than the diameter of the eccentric roller. Therefore, the slight run-on of the motor simply lifts the eccentric roller slightly above the surface of lower yoke plate 47 without moving it upwardly a sufficient distance to bring it into contact with the undersurface of upper yoke plate 46.

Since operation of the device has now automatically stopped, the operator withdraws the beaker from the pipette tip and preferably wipes the pipette tip to remove any liquid clinging to the outer surface and the lower end thereof. Thereafter, a receptacle (not shown) suitable for receiving the diluted sample is placed beneath the pipette and knob 57 is again depressed to close the contacts of the manually operated override switch 59. Motor 22 again rotates drive member 25 and eccentric 27 in a clockwise direction. Well before the upper surface of the eccentric roller reaches the undersurface of upper yoke plate 46, cam 26 swings into contact with the roller 67 of lever 65 to shift the valve member 35 into the second position illustrated in FIGURE 7. Only after the valve is fully shifted does the eccentric engage the upper yoke plate and cause the yoke assembly and the diluent plunger to commence their upward strokes. It is to be noted that the sample displacement plunger remains stationary until the yoke has nearly reached its uppermost position, at which time the upper surface of the upper plate 46 engages stop 51 on shaft 43 to drive that shaft and the sample displacement plunger upwardly.

During upward movement of the yoke assembly, the sample previously drawn into the pipette tip 19 is discharged therefrom followed by a volume of diluent equal to the displacement volume of the diluent plunger. The discharge of diluent ceases when eccentric 27 reaches its uppermost point, at which time upward movement of the yoke assembly and the diluent and sample pistons stops. The drive member 25 nevertheless continues to rotate momentarily until after cam 26 has engaged the roller 67 of lever arm 64 and has thereby driven valve member 35 back into the first position illustrated in FIG- URE 4. Only after the valve member has been returned to such a position does a recess 28 of the drive member 25 reach the rider of switch 30 and permit automatic interruption of the motors operation. The diluter has thus performed a full cycle of operation and again assumes the operative condition illustrated in FIGURE 4.

It is believed from the foregoing that the structure of the present invention constitutes a highly effective automatic diluting device which is simple and substantially foolproof in operation. Since sample is drawn into the pipette or probe at the end of the intake stroke and is discharged at the commencement of the delivery stroke, the pipette is thoroughly rinsed with diluent following the delivery of a sample and the danger of such a sample contaminating the next dilution is thereby avoided.

While in the foregoing, we have disclosed an embodiment of the invention in considerable detail for purposes of illustration, it will be understood by those skilled in the art that many of these details may be varied without departing from the spirit and scope of the invention.

We claim:

1. In an automatic diluting device for diluting a sample with a fixed volume of diluent, a diluent chamber having a reciprocable plunger therein, said plunger having a shaft extending from said chamber, a yoke assembly comprising a pair of yoke plates secured to said shaft and extending transversely with respect thereto, a valve assembly having a valve chamber communicating with said diluent chamber, diluent intake passage means and fluid discharge passage means communicating with said valve assembly, said valve assembly including a valve member shiftable between a first position wherein said valve chamber communicates with said diluent intake passage means and a second position wherein said valve chamber communicates with said fluid discharge passage means, a power driven rotatable drive member having an eccentric element disposed between said yoke plates for reciprocating said plunger as said drive member rotates, said yoke plates being spaced apart a distance substantially greater than the diameter of said eccentric element, and means for shifting said valve member between said first and second positions only when said eccentric is in an intermediate position spaced from both of said cam plates.

2. The structure of claim 1 in which said last-mentioned means includes a cam member mounted upon said drive means, and lever means operatively associated with said cam member for shifting said valve member between said first and second positions.

3. The structure of claim 1 in which said device includes a sample displacement chamber having a reciprocable plunger therein, said plunger having a shaft extending from said chamber and being slidably received in openings in said cam plates, and stop means provided by the shaft of said sample plunger for engaging said yoke assembly and for urging said sample shaft and plunger upwardly and downwardly limited distances as said yoke assembly approaches the upper and lower limits of its range of movement.

4. The structure of claim 3 in which one of said stop means provided by the shaft of said sample plunger is adjustable.

5. The structure of claim 1 in which an, electric motor is operatively associated with said drive member for rotating the same, and switch means are provided for deenergizing said motor when said eccentric element is near its uppermost and lowermost positions.

6. The structure of claim 5 in which said motor, drive member, eccentric, yoke assembly, and switch means are operatively associated to de-energize said motor at points near the uppermost and lowermost positions of said eccentric so that the coasting of said motor will carry said eccentric into positions intermediate said yoke plates following motor de-energization.

7. In a diluting device for diluting a sample with a fixed volume of diluent, a sample chamber and a diluent chamher having reciprocable sample and diluent plungers therein, said plungers having parallel operating shafts extending therefrom, a yoke assembly comprising a pair of transversely extending plates, said assembly being fixed to one of said shafts and slidably receiving the other of said shafts, means for reciprocating said yoke and said one shaft fixed thereto, and stop means provided by the other of said shafts engageable with said yoke assembly for urging said other shaft axially as said yoke approaches the limits of range of reciprocation, said means for reciprocating said yoke and said one shaft comprising an electric motor, a rotatable drive member operatively connected to said motor for rotation thereby, and an eccentric element mounted upon said drive member and disposed between the plates of said yoke assembly for reciprocating said yoke assembly when said drive member is rotated.

'8. The structure of claim 7 in which said one shaft is fixed to said diluent plunger and said other shaft is fixed to said sample plunger.

9. The structure of claim 7 in which said stop means is adjustable to vary the extent of upward and downward movement of said other shaft.

10. The structure of claim 7 in which said eccentric has its maximum dimension measured normal to said plates substantially less than the distance between said plates.

11. The structure of claim 7 in which said eccentric element comprises a roller having a diameter substantially less than the distance between said plates of said yoke assembly.

12. In a diluting device for diluting a sample with a fixed volume of diluent, a sample chamber and a diluent chamber having reciprocable sample and diluent plungers therein, said plungers having parallel operating shafts extending therefrom, a yoke assembly comprising a pair of transversely extending plates, said assembly being fixed to one of said shafts and slidably receiving the others of said shafts, means for reciprocating said yoke and said one shaft fixed thereto, and stop means provided :by the other of said shafts engageable with said yoke assembly for urging the other shaft axially as said yoke approaches the limits of its range of reciprocation, said stop means being adjustable to vary the extent of upward and downward movement of said other shaft and including a pair of stop elements secured to said other shaft aidjacent the upper and lower ends thereof, and a plurality of spacers of different size adapted to be interposed between said yoke assembly and one of said stop elements for varying the extent of movement of said second shaft.

References Cited UNITED STATES PATENTS 1,739,252 12/1929 Mojonnier et al. 222-134 X 2,746,642 5/1956 Parks 222-134 X 3,138,290 6/1964 Coulter 222- X 3,138,294 6/1964 Coulter 222-145 X SAMUEL F. COLEMAN, Primary Examiner.

U.S. Cl. X.R. 222-145 

